When software developers are creating an application, it is possible to incorporate business rules and logic directly into the software application. The problem with this approach is that when the business rules or layouts for the application change, then the user interface, program displays, and business logic must be changed within the application itself. These modifications of the application can be time-consuming and expensive. In software engineering, it is valuable to be able to separate the business rules and the user interface from the application.
In a configuration where the presentation logic and business rules are separated from the application or client, the business logic and presentation layer can be changed without requiring the application layer to be reprogrammed. For example, in a situation using client/server software, the graphical client often resides on a client computer and can request data from a database located at a separate location on a server. If the business rules are programmed at the server level, as part of the database, or as a middleware layer, then it is much easier to modify the business rules without modifying the application or presentation layer.
Another example of separating the application or presentation layer from the business logic layer is a web site that is database enabled. The presentation and formatting of web pages can be separated from the business logic and database.
Separating the database layer, business rule layer, presentation layer, and program logic provides an increased level of maintainability. Unfortunately, the added layers can also add a certain amount of complexity to the interaction between these layers and the technical support of the layers. A side effect of this complexity is that each layer creates multiple independent processes to perform the services and functions for the respective software layer. Several processes can be used by the presentation layer to create electronic documents or web pages, and by a database to perform database queries and handling. In addition, the business rules layer can perform data processing and data checking using multiple processes. If any one of these processes terminates abnormally or experiences other error conditions, this is likely to halt the function of all or a portion of the entire system.
Support personnel and others who maintain the hardware and software underlying such a system can find it difficult to maintain the multitude of processes that exist in this type of complex system. Often the support personnel are manually notified of a process malfunction or crash when the system does not operate properly and ceases providing services, web pages or other functions to end users. Manual notification often takes place through a telephone call from a user who as noticed system problems. Notification and recovery of a process failure at this point in time can create lost business revenues and other significant business disruption. Support personnel have found it difficult to maintain these processes easily and efficiently because of the number of existing processes and the lack of timely information about those processes.